Traditionally, the flooring industry has successfully used an anti-fracture uncoupled support structure disposed between an underlying subfloor and a main floor to protect the main floor from cracking or failing as the subfloor shifts and settles. The support structure decouples the subfloor from the main floor, thereby isolating the subfloor movement from the main floor. Main floors made up of tile are particularly vulnerable to the effects of such subfloor movement.
FIG. 1 shows an example of a commonly-used support structure, as reproduced from and described in U.S. Pat. No. 6,434,901 by Schluter. Schluter describes a support plate made of a foil-like plastic material with protrusions that extend from the material in at least two orientations and intersect to form cavities. The support plate lies between a subfloor and a main floor and decouples the subfloor from the main floor. The support plate is attached to the subfloor with a type of adhesive, e.g., mortar, through a webbing on the underside of the plate. The support plate is filled and covered with mortar to hold the main floor thereon.
In recent years, heated flooring has become popular, in which heating structures are installed beneath the main floor to support heating cables that provide heat. In most cases, an electric heating cable is laid in the heating structure in a typical back-and-forth pattern underneath the area of the main floor to be heated. The heating cable is connected to a thermostat that provides temperature control. A common heating structure is a mat that has the heating cable built into the mat or between two layers of the mat glued together. Examples of such mats are provided by Nuheat™, SunTouch™, Thermosoft™, Warmly Yours™, and WattsRadiant™. However, since used with the support structure, such mats make up another layer to be added between the subfloor and the main floor. The construction of such multiple layers can result in added cost and installation time. Such multiple floor layers can also result in an uneven main floor caused by the elevation difference between the heated areas that include the mats and the unheated areas that do not. Moreover, with irregular shaped rooms or pipes and vents that protrude into the floor, such mats may require customization to properly cover the desired floor area. Such customization comes at substantial cost and required lead time. If changes occur to the floor after a customized mat is created, the customized mat must be modified. This is problematic because the customized mat cannot be modified easily and cannot be so modified without voiding the mat's warranty. Since changes in floor design frequently occur during construction, it then becomes necessary to either modify the customized mat or order a new one.
As an alternative to mats, the flooring industry has introduced another heating structure, cable strips, for laying heating cable. Cable strips are narrow plastic (or similar material) strips that include holders at spaced intervals to hold a cable. The strips are laid along the perimeter of the floor area to be heated. A heating cable is then strung in a typical back-and-forth pattern across the floor area between the cable strips and placed in the strips' holders at the floor perimeter. Examples of such cable strips are provided by Nuheat™ and Flextherm™. These cable strips provide a flexible arrangement for any shape of floor, thereby avoiding the customization sometimes required for mats. However, such cable strips can leave portions of the heating cable exposed on top of the floor. Also, the cables can be difficult to bond properly to the subfloor. In additional, like the mats, such strips can result in an uneven main floor caused by the elevation difference between the heated floor areas that include the cable and cable strips and the unheated floor areas that do not. Also, like the mats, since used with the support structure, the cable and cable strips make up another layer to be added at additional cost and installation time.
As another alternative, panels have been introduced as heating structures for laying heating cable. One such panel is described in WO 02/37032 by Altepost, which describes a modular heating panel having a flat rectangular base body and cavities in a grid-like channel configuration for holding thermal conduits. Another such panel is described in U.S. D541,396 by Fawcett, which describes a radiant heat floor panel having flower-shaped elements and channels around and between the elements through which thermal elements run. Another such panel is manufactured by Schluter™, which has circular elements spaced apart by channels through which heating tubes run. Another such panel is described in U.S. Pat. No. 6,539,681 by Siegmund, which describes a spacer plate having spacers on the bottom of the plate to form a hollow floor and grooves in the top surface of the plate to hold heating or cooling pipes. These panels provide a quick way to cover large areas with heating elements. However, like mats, such panels may make up another layer, in addition to the support structure, to be added at additional cost and installation time. As before, there may also be the uneven main floor possibility with the added panel layer.
Accordingly, there is a need for an effective way to lay cables that avoids the above-mentioned drawbacks.